1. Field of the Invention
This invention relates to hot wire anemometers of the type employed to measure wind velocity turbulence and the like and more particularly to such anemometer and a method for constructing the same that affords improved high temperature operation.
2. Description of the Prior Art
U.S. Pat. No. 3,286,214 discloses a resistance thermometer structure formed in a rod shaped ceramic element in which the conductive portions of the device are sealed by employment of sintered glass-like material. All conductive parts of the patented device are enclosed.
U.S. Pat. No. 3,435,400 discloses a thermal probe constructed on a hypodermic needle or the like for measurement of fluid flow velocity, such as blood flow in animal and in man. The patented probe is formed on the tip of an oblique surface formed on the hypodermic needle; a thin homogeneous metallic membrane of platinum is coated on the oblique surface and the resistance across the membrane is measured to afford measurement of the fluid flow.
U.S. Pat. No. 3,553,827 discloses a thermo couple supported by ceramic spacers within a sheath of tantalum. All electric elements in the thermo couple are enclosed within the sheath.
Hot film sensors employing a thin film formed on a quartz rod or wedge are commercially available from Thermo-Systems, Inc. of St. Paul, Minn. Because the temperature sensitive material is in the form of a thin film, the temperature operating range of such probes is limited to about 400.degree. C.